BANGOR, Maine — A convicted sex offender who was found guilty in federal court on child pornography charges pleaded guilty Monday in state court to 10 counts of sexual abuse of a minor under a plea deal in which his sentence is expected to run concurrently with his federal period of incarceration.

Sentencing dates have not been set in either court for Carey E. Gonyer, 44, of Charleston.

Gonyer’s plea agreement calls for him to be sentenced to five years on the state sex abuse charges, Penobscot County Assistant District Attorney Alice Clifford, who prosecuted the case in state court, said Monday after Gonyer entered his guilty pleas. She said the agreement calls for the defendant to serve his state sentence at the same time he is serving what is expected to be a much longer sentence on the federal charges.

He faces a mandatory minimum of 15 years and a maximum of 30 years in federal prison on the sexual exploitation charges and up to 10 years in prison on the possession of pornography charge. He also faces fines of up to $250,000 on each federal count.

After 1½ days of testimony, Gonyer was found guilty in July by a jury in U.S. District Court in Bangor on three counts of sexual exploitation of a minor in the production of pornography and one count of possession of child pornography.

The state and federal charges involve one male victim who was 15 years old when the crimes took place, according to a previously published report.

Gonyer served 2½ years in federal prison for possession of child pornography. He was sentenced in December 2006 after pleading guilty to the charge the previous May. Gonyer was released in July 2008.

The incidents that led to the charges in state and federal court occurred in 2010 and 2011, when the boy worked on the dairy farm where Gonyer worked and lived.

The boy, who is now 17, told jurors in July at Gonyer’s trial in federal court that he began working at the Valley View Farm in Charleston in late May or early June 2010 on weekends. When school was out, he worked almost daily throughout the summer as a farmhand.

Under direct examination, he said the first sexual assault occurred in the early summer when he spent the night at the small apartment Gonyer had on the farm when the boy’s mother and stepfather were away for a weekend. The sexual assaults continued the next summer when he returned to work on the farm, the teenager testified.

The federal indictment alleged the incidents that led to the sexual exploitation counts occurred in June, July and September 2011. The production charges involve two photos the boy said he took with his cellphone and sent to Gonyer’s cellphone and one taken with Gonyer’s phone, all at the defendant’s request.

The teen testified that Gonyer told him to delete text and photo messages after sending them, which he did. He said Gonyer threatened to tell the boy’s mother he had been smoking cigarettes if he told anyone they were having sex. Once, the boy testified, Gonyer threatened to kill his mother if the teen reported the two were having sex.

Jurors deliberated on July 25 for two hours and 40 minutes before announcing their verdict in U.S. District Court in Bangor.